package main

import (
  "flag"
  "fmt"
  "os"
  "strings"
)

type Command struct {
  // Run runs the command.
  // The args are the arguments after the command name.
  Run func(cmd *Command, args []string) bool

  // UsageLine is the one-line usage message.
  // The first word in the line is taken to be the command name.
  UsageLine string

  // Short is the short description shown in the 'go help' output.
  Short string

  // Long is the long message shown in the 'go help <this-command>' output.
  Long string

  // Flag is a set of flags specific to this command.
  Flag flag.FlagSet

}

// Name returns the command's name: the first word in the usage line.
func (c *Command) Name() string {
  name := c.UsageLine
  i := strings.Index(name, " ")
  if i >= 0 {
    name = name[:i]
  }
  return name
}

func (c *Command) Usage() {
  fmt.Fprintf(os.Stderr, "Example: weed %s\n", c.UsageLine)
  fmt.Fprintf(os.Stderr, "Default Usage:\n")
  c.Flag.PrintDefaults()
  fmt.Fprintf(os.Stderr, "Description:\n")
  fmt.Fprintf(os.Stderr, "  %s\n", strings.TrimSpace(c.Long))
  os.Exit(2)
}

// Runnable reports whether the command can be run; otherwise
// it is a documentation pseudo-command such as importpath.
func (c *Command) Runnable() bool {
  return c.Run != nil
}
